The present invention described herein relates generally to an apparatus for dynamoelectric machines. More specifically, present invention relates to an apparatus for compressing the lamination stack in the core of a dynamoelectric machine.
Stator core laminations, i.e., punchings, are generally arranged in a plurality of annular arrays thereof forming sets or packets of adjacent stator core laminations. The sets of annular arrays of laminations are axially spaced one from the other by space blocks and installed in a generator stator frame. The space blocks define ventilation passages for directing a cooling flow radially through the stator. Typically, the assembly of the laminations is performed manually by disposing the laminations on dovetail-shaped keybars which have male projections complementary to the female projections along the outer diameter of the individual laminations. During assembly, the lamination stack can develop undesirable waves caused by burrs created during the punching process. In addition, trapped air may also cause undesirable waves in the lamination stack.
The current known method for compressing the core during restack is to use loose pipes stacked under the top finger plates/clamping ring. Technicians must then manually torque each of the finger plate/clamp ring bolts, and re-torque the bolts multiple times in series to assure an equal pressure throughout the stack. A downside to this method is that (1) there is a high incident probability of the loose pipes falling with a domino effect into the core inner diameter during set up thereby endangering the technicians setting up for the compression operation, (2) the amount of pressure placed on the stack is of an unknown and uneven quantity, and (3) it involves a high number of hours for the set up needed for each compression cycle, which includes the removal of the pipes and associated hardware and the removal of the finger plates/clamp ring as well as re-installing all the aforementioned elements for the subsequent compression cycle.